Rfid tag communication device

ABSTRACT

According to an embodiment, a wireless tag communication device includes a first antenna that emits radio waves towards a first region of a conveyance path for wireless tags and a second antenna that emits radio waves towards a second region of the conveyance path on downstream of the first region along the conveyance path. A shield prevents the radio waves emitted from the first antenna from reaching a first portion of the first region while permitting the radio waves to reach a second portion of the first region. A controller is configured to select a tag ID read via the first antenna as a target tag ID, designate the target tag ID by communication via the second antenna, and then write tag information via the second antenna to the wireless tag corresponding to the designated target tag ID.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2020-113942, filed on Jul. 1, 2020, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a radio frequencyidentifier (RFID) tag communication device.

BACKGROUND

A system in which different items to be individually managed have anRFID tag attached to each article. Each RFID tag stores item informationthat is unique to the respective item within a memory of the RFID tag.RFID tags to be used in this kind of system are written with informationby RFID tag communication devices. In such a RFID tag communicationdevice labels equipped with an RFID tag are conveyed at a predeterminedinterval through the RFID tag communication device for writing. The RFIDtagged labels can be arranged along strips of label paper of the like.The RFID tag communication device writes the unique information to eachRFID tag by wireless communication via an antenna typically placed neara middle position for the conveyance of the labels. Such RFID-taggedlabels can also be printed with information corresponding to or matchingthe unique item information that is written to an RFID tag. A printedlabel including an RFID tag can then be attached to an itemcorresponding to that unique information. Thus, individual managementand tracking of each tagged/labelled item can be realized.

In some cases, the labels have various sizes, and the RFID tagcommunication device is configured to write article information to RFIDtags attached to the labels of various sizes. However, since the labelsize varies, the pitch between the RFID tags that are sequentiallyconveyed also varies. If the pitch is narrower, more than one RFID tagsmay be present in a communication area of the antenna. In such a case,the RFID tag communication device may not be able to identify thecorrect or intended target RFID tag to communicate for writing thecorresponding unique item information and may write information to anon-targeted or unintended RFID tag in error. Hence, there is a need foran RFID tag communication device that can stably communicate with atarget RFID tag for writing article information regardless of a size ofa label or a pitch between RFID tags on the labels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic configuration of an RFID tag communicationdevice according to a first embodiment.

FIG. 2 depicts an example of a label paper according to a firstembodiment.

FIG. 3 is a block diagram of an example circuit configuration of acontroller according to a first embodiment.

FIG. 4 depicts a data structure of a list table according to a firstembodiment.

FIG. 5 is a flowchart of a label dispensing process according to a firstembodiment.

FIG. 6 is a flowchart of a label dispensing process according to a firstembodiment.

FIG. 7 is a flowchart of a writing process according to a firstembodiment.

FIG. 8 depicts a shielding plate according to a second embodiment.

FIG. 9 depicts a schematic configuration of an RFID tag communicationdevice according to a second embodiment.

FIG. 10 depicts a data structure of a list table according to a secondembodiment.

FIG. 11 is a flowchart of a label dispensing process according to asecond embodiment.

FIG. 12 is a flowchart of a label dispensing process according to asecond embodiment.

FIG. 13 depicts a part of a RFID tag communication device according to athird embodiment.

FIG. 14 depicts a part of a RFID tag communication device according to afourth embodiment.

DETAILED DESCRIPTION

According to an embodiment, a wireless tag communication device includesa first antenna that is configured to emit radio waves towards a firstregion of a conveyance path for wireless tags and a second antenna thatis configured to emit radio waves towards a second region of theconveyance path on a downstream side of the first region in a tagconveyance direction along the conveyance path. A shield is configuredto block the radio waves emitted from the first antenna from reaching afirst portion of the first region while permitting the radio waves fromthe first antenna to reach a second portion of the first region. Acontroller is configured to select a tag ID read via the first antennafrom a wireless tag on the conveyance path as a target tag ID, designatethe target tag ID by communication via the second antenna, and write taginformation via the second antenna to the wireless tag corresponding tothe designated target tag ID.

First Embodiment

FIG. 1 depicts a schematic configuration of an RFID tag communicationdevice 100 according to the first embodiment. FIG. 2 depicts an exampleof a label paper 1 in the present embodiment.

As shown in FIG. 2, the label paper 1 includes a strip-shaped mount 2and a plurality of rectangle labels 3 attached to the surface of themount 2. The labels 3 are arranged in a row at a constant interval alonga longitudinal direction of the mount 2, that is a conveyance directionY of the labels 3. In the example, each of the labels 3 has a length ofLa in the conveyance direction Y (that is a total length), and therespective labels 3 are arranged at an interval d therebetween. Thelabel paper 1 has a mark 5 on a leading-edge side of each of the labels3. The marks 5 are on the surface of the mount 2. Each mark 5 indicatesa position of a leading-edge of one of the labels 3.

Each of the labels 3 includes an RFID tag 4. Each RFID tag 4 includes astorage medium and a wireless communication function. The RFID tag 4 mayalso be referred to as an integrated circuit (IC) tag and, in thisexample, is a passive tag that does not include a battery. The RFID tag4 includes an antenna 41, an IC chip 42, and an inlay 43. The inlay 43is used for installing (connecting) the antenna 41 and the IC chip 42within the RFID tag 4. The IC chip 42 is an integrated circuit includinga processor, a storage unit, an interface, and the like. The processorof the IC chip 42 executes programs such as operation control. Thestorage unit of the IC chip 42 stores programs, tag IDs, and other dataexecuted by the processor. The tag ID is RFID tag-specific data (e.g., aunique serial number, code, or the like). The tag ID is generallywritten to the storage unit during the manufacturing process of the RFIDtag 4. An interface of the IC chip 42 is connected to the antenna 41.

A mounting position of the RFID tag 4 on the label 3 is determinedaccording to a type, a size, and the like of the label paper 1. In theexample of FIG. 2, the RFID tag 4 is arranged on the label paper 1 at aposition of a distance Lb (Lb<La) from the leading-end of the label 3with respect to the total length La in a direction which is the same asthe conveyance direction Y of the label 3. The antenna 41 of the RFIDtag 4 is arranged so that the longitudinal direction of the antenna 41is orthogonal to the conveyance direction Y. On the label paper 1, aninterval between the RFID tags 4 attached to the adjacent labels 3, thatis a pitch of the RFID tags 4, is constant at La+d. The pitch may varydepending on the type, size, and the like of the label paper 1.

The label paper 1 is set in the RFID tag communication device 100, forexample, in a state of being wound in a rolled shape as shown in FIG. 1.

As shown in FIG. 1, the RFID tag communication device 100 includes apaper holding unit 11, a conveyance roller 12, a pinch roller 13, aplaten roller 14, and a motor 15. The paper holding unit 11 holds thelabel paper 1 wound in a rolled shape. The conveyance roller 12 rotatesin a direction of the illustrated arrow with the power of the motor 15in a state of sandwiching the label paper 1, which has been pulled outfrom the paper holding unit 11, with the pinch roller 13. By thisrotation, the label paper 1 sandwiched between the conveyance roller 12and the pinch roller 13 is conveyed from the upstream side nearer to thepaper holding unit 11 to the downstream side nearer to the platen roller14 in the conveyance direction Y. The platen roller 14 rotates in theillustrated arrow direction with the power of the motor 15. By thisrotation, the label paper 1 conveyed to the platen roller 14 is furtherconveyed to the downstream side of the platen roller 14. A labeldispensing port is provided to the downstream side of the platen roller14 where the label paper 1 is dispensed outside the RFID tagcommunication device 100. The conveyance roller 12, the pinch roller 13,and the platen roller 14 form a conveyance path 20 of the label paper 1.The conveyance path 20 may also be referred to as a conveyance path ofthe label 3 or a conveyance path of the RFID tag 4.

The RFID tag communication device 100 includes a head driver 16, a printhead 17, a sensor signal input unit 18, and a label sensor 19. The headdriver 16 is connected to the print head 17. The print head 17 isprovided facing the platen roller 14 such that the label paper 1 can besandwiched therebetween. The print head 17 is driven by the head driver16 and performs printing on the label 3 conveyed to the position of theplaten roller 14.

The sensor signal input unit 18 is connected to the label sensor 19. Thelabel sensor 19 is provided near the conveyance roller 12. The labelsensor 19 detects the mark 5 on the label paper 1. The label sensor 19outputs a detection signal to the sensor signal input unit 18 when themark 5 is detected. The sensor signal input unit 18 receives thedetection signal output from the label sensor 19. The sensor signalinput unit 18 outputs the received detection signal to a controller 30.

The RFID tag communication device 100 further includes a first antenna21, a second antenna 22, a first reader and writer 23, and a secondreader and writer 24. The first antenna 21 is provided on the conveyancepath 20 between the conveyance roller 12 and the platen roller 14. Thefirst antenna 21 is provided at a position where communication with theRFID tag 4 of the label 3 being conveyed along the conveyance path 20 isavailable.

The second antenna 22 is provided on the downstream side of theconveyance path 20 with respect to the first antenna 21. The secondantenna 22 is provided at a position where communication with the RFIDtag 4 of the label 3 being conveyed along the conveyance path 20 isavailable.

The first reader and writer 23 is connected to the first antenna 21. Thefirst reader and writer 23 performs wireless communication with the RFIDtag 4 via the first antenna 21. With this wireless communication, thefirst reader and writer 23 reads a tag ID from the RFID tag 4.

The second reader and writer 24 is connected to the second antenna 22.The second reader and writer 24 performs wireless communication with theRFID tag 4 via the second antenna 22. With this wireless communication,the second reader and writer 24 writes data to the RFID tag 4. This datais referred to as tag writing data herein.

The RFID tag communication device 100 further includes the controller30. The controller 30 is connected to the motor 15, the head driver 16,the sensor signal input unit 18, the first reader and writer 23, and thesecond reader and writer 24.

The controller 30 controls the motor 15 to control a conveyance on andoff status of the label paper 1. The controller 30 controls the motor 15to switch or change the conveyance speed of the label paper 1 as needed.The controller 30 detects the position of the label 3 being conveyed onthe conveyance path 20 according to the conveyance speed of the labelpaper 1 and input timing of the detection signal obtained via the sensorsignal input unit 18. Then, the controller 30 controls the head driver16 and prints data of characters, images, or the like on the printingsurface of the label 3 that has been conveyed to the position of theplaten roller 14. The data printed on the printing surface of the label3 is referred to as label printing data herein. The label printing datais provided from the controller 30 to the print head 17 via the headdriver 16.

According to the present embodiment, a shielding plate 61 is providedbetween the first antenna 21 and the conveyance path 20 of the labelpaper 1. The shielding plate 61 is provided closer to the conveyancepath 20 between the first antenna 21 and the conveyance path 20. Theshielding plate 61 is, for example, a rectangle metal plate. Theshielding plate 61 is disposed so that its long side and short side aresubstantially parallel to the width direction and the conveyancedirection Y of the label paper 1, respectively. The length of the longside is at least longer than the length of the inlay 43 in thelongitudinal direction in the RFID tag 4. The length of the short sideis at least longer than the length of the inlay 43 in the shortdirection.

The shielding plate 61 shields a portion of an area where thecommunication between the first antenna 21 and the RFID tag 4 beingconveyed along the conveyance path 20 is available. Such an area isreferred to as a communication available area, and the shielded portionof the communication available area forms a communication unavailablearea. For example, as shown in FIG. 1, the shielding plate 61 is at aposition where the communication unavailable area Ab is formed betweenthe communication available areas Aa and Ac along the conveyance path20. In the RFID tag 4 that passes through the communication unavailablearea Ab, a received signal strength indicator (RSSI) of a radio waveradiated from the first antenna 21 decreases.

A shielding plate is not provided for, or in conjunction with, thesecond antenna 22. Therefore, in a communication available area Ad ofthe second antenna 22, there is no communication unavailable area.

FIG. 3 is a block diagram of an example circuit configuration of thecontroller 30. The controller 30 includes a processor 31, a memory 32, acommunication interface 33, an operation panel 34, and first to fifthI/O ports 351 to 355. The controller 30 connects the processor 31, thememory 32, the communication interface 33, the operation panel 34, andthe I/O ports 351 to 355 to a system bus 36. The system bus 36 includesan address bus, a data bus, and the like.

The processor 31 corresponds to a central portion of the controller 30.The processor 31 controls each unit so that various functions as theRFID tag communication device 100 are to be realized according to anoperating system or an application program. The processor 31 is, forexample, a central processing unit (CPU).

The memory 32 corresponds to a storage portion of the controller 30. Thememory 32 includes a nonvolatile memory area and a volatile memory area.The memory 32 stores an operating system or an application program in anonvolatile memory area. The memory 32 stores data required for theprocessor 31 to execute processes for controlling each portion in avolatile memory area. The memory 32 uses the volatile memory area as awork area where the data is appropriately rewritten by the processor 31.The nonvolatile memory area is, for example, a read only memory (ROM).The volatile memory area is, for example, a random-access memory (RAM).

The communication interface 33 is for communication with an externaldevice (or an upper level device). For example, the communicationinterface 33 is used for receiving the label printing data and the tagwriting data from the external device.

The operation panel 34 includes an interface function to be operated bya user or an operator. The operation panel 34 includes, for example, adisplay device equipped with a touch panel. Using the display device, astart instruction of a label dispensing process or the like is inputtedto the operation panel 34 by a user or an operator.

The first to fifth I/O ports 351 to 355 are circuits for sending andreceiving data signal between the processor 31 and devices connected tothe I/O ports 351 to 355. For example, the motor 15 is connected to thefirst I/O port 351. The processor 31 outputs a drive-on signal, adrive-off signal, and the like to the motor 15 via the first I/O port351. The head driver 16 is connected to the second I/O port 352. Theprocessor 31 outputs the label printing data and the like to the headdriver 16 via the second I/O port 352. The sensor signal input unit 18is connected to the third I/O port 353. The processor 31 receives thedetection signal from the sensor signal input unit 18 via the third I/Oport 353. The first reader and writer 23 is connected to the fourth I/Oport 354. The processor 31 inputs data such as a tag ID read by thefirst reader and writer 23 via the fourth I/O port 354. The secondreader and writer 24 is connected to the fifth I/O port 355. Theprocessor 31 outputs the tag writing data and the like to the secondreader and writer 24 via the fifth I/O port 355.

The controller 30 has a list table 51 stored in the memory 32. FIG. 4depicts an example data structure of the list table 51. The list table51 includes areas for describing tag IDs, the numbers of times ofcommunication failure n, and process completion flags F.

FIGS. 5 and 6 are flowcharts of the label dispensing process that isexecuted by the processor 31 according to a control program. FIG. 7 is aflowchart of a writing process executed as a subroutine of the labeldispensing process. These processes according to the present embodimentare examples and are not limited thereto so long as the same orsubstantially the same results can be obtained.

As an initial step, the RFID tag communication device 100 receives thetag writing data and the label printing data of the labels 3 for apredetermined number of label sheets from the external device and storesthe data in the memory 32. In this state, if the start instruction ofthe label dispensing process is received via the operation panel 34 (seeFIG. 3), the processor 31 starts the label dispensing process as shownin the flowchart of FIG. 5.

In Act 1 of the flowchart, the processor 31 clears the list table 51. InAct 2, the processor 31 activates the motor 15 to convey the label paper1 along the conveyance path 20.

Subsequently, in Act 3, the processor 31 controls the first reader andwriter 23 so that the tag ID is read from the RFID tag 4 by the wirelesscommunication with the first antenna 21. According to the control, theradio wave including a tag ID reading command is radiated from the firstantenna 21. If the RFID tag 4 receives the radio wave, a response waveis sent back (returned) from the RFID tag 4, and the first reader andwriter 23 reads the tag ID from the response wave received via the firstantenna 21. The tag ID read by the first reader and writer 23 is givento the processor 31. In Act 4, the processor 31 calculates the number oftag IDs read by the first reader and writer 23, that is, a number ofread tag IDs T.

The processor 31 determines whether the number of read tag IDs T is “0”in Act 5. If the number of read tag IDs T is “0,” that is, no tag ID hasbeen read by the first reader and writer 23 (YES in ACT 5), theprocessor 31 proceeds to Act 6 and determines whether the list table 51is empty.

If the processor 31 determines that no data has been written to the listtable 51 and that the list table 51 is empty (YES in Act 6), theprocessor 31 returns to Act 3. The processor 31 controls the firstreader and writer 23 again to read the tag ID from the RFID tag 4 in Act3.

In this manner, the processor 31 controls the first reader and writer 23to repeat the wireless communication via the first antenna 21 until thetag ID of the RFID tag 4 is read. Then, if at least one tag ID is read(NO in Act 5), the processor 31 proceeds to Act 7. In Act 7, theprocessor 31 stores the read tag ID in the tag ID area of the memory 32.In Act 8, the processor 31 sets the number of read tag IDs T as aninitial value of a subtraction counter C. The subtraction counter C isformed, for example, in the memory 32. Thereafter, the processor 31proceeds to Act 21 of FIG. 6.

In Act 21, the processor 31 obtains an unprocessed tag ID among the tagIDs stored in the tag ID area of the memory 32. The obtained unprocessedtag ID is referred to as an unprocessed tag ID in this context. In Act22, the processor 31 determines whether an unprocessed tag ID is presentin the list table 51. If an unprocessed tag ID is not present in thelist table 51 (NO in Act 22), the processor 31 proceeds to Act 23 andadds the unprocessed tag ID to the list table 51. The processor 31 thensets values for the number of communication failures n and the processcompletion flag F correlated with the unprocessed tag ID to “0” in Act24.

The processor 31 reduces (decrements) the subtraction counter C by “1”in Act 25. Then, the processor 31 checks whether the subtraction counterC is “0” in Act 26. If the subtraction counter C is “1” or more (NO inAct 26), it means that there is another unprocessed tag ID still in thelist table 51, and the processor 31 returns to Act 21 and repeats theprocesses until subtraction counter C is 0 (YES in ACT 26).

Referring back to Act 22, if the unprocessed tag ID is present in thelist table 51 (YES in Act 22), the processor 31 proceeds to Act 27. Theprocessor 31 determines whether the process completion flag F correlatedwith the unprocessed tag ID is set to “1” in Act 27.

If the process completion flag F is not set to “1” (NO in Act 27), theprocessor 31 proceeds to Act 28 and obtains the number of communicationfailures n correlated with the unprocessed tag ID. In Act 29, theprocessor 31 checks whether the number of communication failures nexceeds a predetermined number N. The predetermined number N is a valueapproximately equal to the number of reading attempts of a tag ID whichcan be assumed to be experience when normally conveyed together with thelabel paper 1 along the conveyance path 20 to pass through thecommunication unavailable area Ab of the first antenna 21.

If the number of communication failures n does not exceed thepredetermined number N (NO in Act 29), the processor 31 proceeds to Act25 and repeats the processes.

If the number of communication failures n exceeds the predeterminednumber N (YES in Act 29), the processor 31 proceeds to Act 30. In Act30, the processor 31 designates the unprocessed tag ID as a target tagID and writes the target tag ID to the target tag area of the memory 32.Then, the processor 31 sets the process completion flag F correlatedwith the unprocessed tag ID (that is the target tag ID) of the listtable 51 to “1” in Act 31. Thereafter, the processor 31 activates thewriting process in Act 32.

The processor 31 that has activated the writing process proceeds to Act25 and repeats the processes.

Referring back to ACT 27, if the process completion flag F correlatedwith the unprocessed tag ID present in the list table 51 is set inadvance (YES in ACT 27), the processor 31 directly proceeds to Act 25and repeats the processes.

If the subtraction counter C becomes “0” as a result of executing theprocess of Act 25 (YES in Act 26), the processor 31 proceeds to Act 9 ofFIG. 5. Also, as shown in FIG. 5, in a case where no tag ID has beenread with the first antenna 21, that is T=0 (YES in ACT 5) and some dataare present in the list table 51, that is the list table 51 is not empty(No in Act 6), the processor 31 proceeds to Act 9.

In Act 9, the processor 31 detects a tag ID that had not been read inthe reading process of Act 3 among the tag IDs described in the listtable 51. This tag ID is referred to as an unreadable tag ID herein. InAct 10, the processor 31 determines whether an unreadable tag ID ofwhich process completion flag had been set to “1” is present in the listtable 51. If there is an unreadable tag ID with the process completionflag set to “1” in the list table 51 (YES in Act 10), the processor 31proceeds to Act 11 and deletes a record of that unreadable tag ID fromthe list table 51. Thereafter, the processor 31 proceeds to Act 12.

If the unreadable tag ID of the process completion flag “1” is not inthe list table 51 (NO in Act 10), the processor 31 skips the process ofAct 11 and proceeds to Act 12.

In Act 12, the processor 31 adds “1” to the number of communicationfailures n corresponding to the unread tag ID among the tag IDs in thelist table 51. In Act 13, the processor 31 checks whether the labeldispensing process has been completed. The label dispensing process isfor writing the tag writing data received from the external device tothe RFID tags 4 and dispensing a predetermined number of labels 3 forwhich the label printing data has been printed on the printing surfacesof the labels 3.

If the label dispensing process has not yet been completed (NO in Act13), the processor 31 returns to Act 3 and repeats the processes.

Once the label dispensing process is complete (YES in ACT 13), theprocessor 31 proceeds to Act 14 and stops the motor 15 to stop theconveyance of the label paper 1.

FIG. 7 is a flowchart of the writing process according to the firstembodiment. In Act 41, the processor 31 controls the second reader andwriter 24 to transmit the radio wave for designating the target tag IDto the RFID tag 4. Based on this control, the radio wave including thetarget tag ID and a command that designates the target tag ID isradiated from the second antenna 22. If the RFID tag 4 that stores thedesignated target tag ID in the IC chip 42 receives this radio wave, aresponse wave will be returned from the RFID tag 4. The response wavewill then be received by the second antenna 22 and output to theprocessor 31 as the response signal via the second reader and writer 24.

In Act 42, the processor 31 waits for the response signal from the RFIDtag 4. Once the response signal has been received via the second antenna22 and the second reader and writer 24 (YES in Act 42), the processor 31proceeds to Act 43 and controls the second reader and writer 24 to writethe tag writing data to the RFID tag 4. Based on this control, a radiowave including the tag writing data and the tag writing command isradiated from the second antenna 22. This radio wave is received by theRFID tag 4 that stores the designated target tag ID by the IC chip 42,and the tag writing data is written to the IC chip 42 (Act 43). Wheneverthe writing process is activated in Act 32 (see FIG. 6), the processor31 executes these steps as shown in FIG. 7.

The label 3 which has the tag writing data written to the RFID tag 4 isfurther conveyed to the downstream of the conveyance path 20. When thelabel 3 reaches the position of the platen roller 14, the print head 17operated by the head driver 16 prints the label printing data to theprinting surface of the label 3. In this manner, the tag writing data iswritten to the RFID tag 4, and the label 3 with the label printing dataprinted on the printing surface is dispensed from the label dispensingport to the outside of the RFID tag communication device 100.

Once the predetermined number of sheets of the labels 3, with the tagwriting data and the label printing data received from the externaldevice recorded thereon, has been dispensed from the label dispensingport, the RFID tag communication device 100 ends the label dispensingprocess.

After the end of the label dispensing process, the controller 30 rotatesthe motor 15 in a reverse direction and conveys the label paper 1 in theopposite direction such that the label 3 at the leading position amongthe labels 3 remaining on the conveyance path 20 returns to the upstreamside with respect to the label sensor 19. Thereafter, the processor 31may stop the conveyance of the label paper 1. The reverse rotationcontrol of the motor 15 may be performed by the processor 31 before theprocess of Act 2 starts.

In the present embodiment, the RFID tag communication device 100includes the first antenna 21 and the second antenna 22 along theconveyance path 20 where the RFID tags 4 are conveyed together with theplurality of labels 3 attached to the label paper 1. The second antenna22 is provided on the downstream side with respect to the first antenna21 in the conveyance direction Y of the conveyance path 20. Theshielding plate 61 that blocks the radio wave emitted from the firstantenna 21 to the RFID tag 4 is disposed so that at least a portion(such as a middle portion as shown in FIG. 1) between the communicationavailable areas Aa and Ac where the first antenna 21 can perform thecommunication with the RFID tag 4 becomes the communication unavailablearea Ab, that is the area where the first antenna 21 cannot perform thewireless communication with the RFID tag 4.

In the present embodiment, the controller 30 identifies one of the tagIDs read from the plurality of RFID tags 4 by the communication via thefirst antenna 21. For example, the controller 30 identifies a single tagID that has passed through the communication unavailable area Ab andthus has become temporarily unreadable via the first antenna 21, that isa single tag ID of which the number of communication failures n hasexceeded the predetermined number N, among the tag IDs read from theRFID tags 4 by the communication via the first antenna 21. If the singletag ID is identified, the controller 30 designates that tag ID by thecommunication via the second antenna 22. Then, the controller 30 writesthe tag writing data to a single RFID tag 4 of the identified single tagID, among the plurality of RFID tags 4, that is now connected to thecommunication via the second antenna 22 by the designation of thatspecific tag ID.

In this manner, the RFID tag communication device 100 designates a tagID that has been previously identified by communication via the firstantenna 21 using communication via the second antenna. The RFID tagcommunication device 100 writes the tag writing data to one RFID tag 4according to the designation of the tag ID. Accordingly, the RFID tagcommunication device 100 can correctly identify one RFID tag 4 among thevarious RFID tags 4 as the particular target RFID tag 4 forcommunication and thus more stably communicate with the target RFID tag4 for the writing of the tag writing data.

Furthermore, the RFID tag communication device 100 identifies a RFID tag4 that is assumed to have passed through the communication unavailablearea Ab using the first antenna 21. Accordingly, the pitch of the RFIDtags 4 conveyed together with the labels 3 on the label paper 1 does notnecessarily relate to the designation of the RFID tag 4. Therefore,regardless of the tag pitch on the label paper 1 or the mount 2 of thelabel paper 1 (see FIG. 2), the RFID tag communication device 100 cancorrectly identify and stably communicate with the particular targetRFID tag 4.

In the present embodiment, the RFID tag communication device 100designates the previously identified tag ID by wireless communicationvia the second antenna 22 and the second reader and writer 24. Then, theRFID tag communication device 100 writes tag writing data to the RFIDtag 4, which has responded to the wireless communication via the secondantenna 22 designating the identified tag ID. Accordingly, even if aplurality of RFID tags 4 are present in the communication available areaAd of the second antenna 22, the tag writing data can still be stablywritten to the particular target RFID tag 4. Thus, the radio waveintensity of the second antenna 22 can be increased, and a more stabletag writing operation can be realized.

Second Embodiment

In the first embodiment, the shielding plate 61 is a rectangle metalplate. The shape of the shielding plate 61 is not limited thereto. FIG.8 is a schematic diagram of a shielding plate 62 according to a secondembodiment. The shielding plate 62 includes a rectangular opening 63formed in a central portion of a rectangular plate. The plate may bemade of, for example, metal.

FIG. 9 depicts a schematic configuration of an RFID tag communicationdevice 200 according to the second embodiment. Portions common to theRFID tag communication device 100 of the first embodiment are designatedwith the same reference numerals, and additional descriptions thereofmay be omitted. The RFID tag communication device 200 includes theshielding plate 62 between the first antenna 21 and the conveyance path20 of the label paper 1. The shielding plate 62 is closer to theconveyance path 20 between the first antenna 21 and the conveyance path20. The opening 63 of the shielding plate 62 is positioned above thecenter of a radiation surface of the first antenna 21, and thelongitudinal direction of the opening 63 is identical to the widthdirection of the label paper 1 being conveyed along the conveyance path20.

The shielding plate 62 shields a portion of a communication availablearea where the first antenna 21 can communicate with the RFID tag 4being conveyed along the conveyance path 20 to form both thecommunication unavailable area Ab and the communication available areaAa on the conveyance path 20 as shown in FIG. 9. The communicationavailable area Aa is formed by the opening 63 of the shielding plate 62above the center of the radiation surface of the first antenna 21. Theshape and size of the communication available area Aa is limited by theshape and size of the opening 63. The shielding plate 62 blocks theradio waves emitted from the first antenna 21 and creates thecommunication unavailable area Ab by allowing only part of the emittedradio waves to reach the conveyance path 20 via the limitedcommunication available area Aa. By providing the shielding plate 62 inthis manner, the first reader and writer 23 can read, via the firstantenna 21, the tag IDs from the RFID tags 4 that pass through thelimited communication available area Aa. The first reader and writer 23cannot read the tag IDs from the RFID tags 4 that are passing throughthe communication unavailable area Ab since the radio waves from thefirst antenna 21 are blocked from this area.

FIG. 10 depicts an example data structure of a list table 52 formed inthe memory 32 of the RFID tag communication device 200 according to thesecond embodiment. The list table 52 includes areas for tag IDs, thenumbers of communication attempts n, and read flags F.

FIGS. 11 and 12 are flowcharts of a label dispensing process that isexecuted by the processor 31 of the RFID tag communication device 200according to the control program. These processes according to thepresent embodiment are examples and are not limited thereto so long asthe same or substantially the same results can be obtained.

As an initial step, the RFID tag communication device 200 receives thetag writing data and the label printing data for a predetermined numberof labels 3 from an external device and stores the data in the memory32. In this state, if a start instruction of the label dispensingprocess is received via the operation panel (see FIG. 3), the processor31 starts the label dispensing process as shown in the flowchart of FIG.11.

The processes of Acts 51 to 58 executed by the processor 31 are the sameas those of Acts 1 to 8 of FIG. 5 executed by the same processor 31.Therefore, the descriptions thereof are not repeated.

In Act 58, once the processor 31 sets the number of read tag IDs T as aninitial value of the subtraction counter C, the processor 31 proceeds toAct 71 of FIG. 12. In Act 71, the processor 31 obtains an unprocessedtag ID from the tag IDs stored in a tag ID area of the memory 32 (seeFIG. 3). In Act 72, the processor 31 determines whether the obtainedunprocessed tag ID is present in the list table 52. If the unprocessedtag ID is not present in the list table 52 (NO in Act 72), the processor31 proceeds to Act 73 and adds the unprocessed tag ID to the list table52. The processor 31 then sets the number of communication attempts ncorrelated with the unprocessed tag ID to “0” in Act 74. Further, theprocessor 31 sets the read flag F correlated with the unprocessed tag IDto “1” in Act 75.

The processor 31 subtracts “1” from the subtraction counter C in Act 76.Then, the processor 31 confirms checks whether the subtraction counter Cequals “0” in Act 77. If the subtraction counter C is “1” or more (NO inAct 77), it means that there is another unprocessed tag ID present inthe list table 52, and the processor 31 returns to Act 71 and repeatsthe processes.

Referring back to Act 72, if an unprocessed tag ID is present in thelist table 52 (YES in Act 72), the processor 31 proceeds to Act 78 andadds “1” to the number of communication attempts n correlated with theunprocessed tag ID. Thereafter, the processor 31 proceeds to Act 75 andexecutes the processes of Acts 75 to 77.

If the subtraction counter C becomes “0” as a result of executing theprocess of Act 77 (YES in Act 77), the processor 31 proceeds to Act 59of FIG. 11. Also, as shown in FIG. 11, in a case where no tag ID hasbeen read by the first antenna 21, that is T=0 (YES in ACT 5) and somedata are present in the list table 52, that is the list table 52 is notempty (NO in Act 56), the processor 31 proceeds to Act 59.

In Act 59, the processor 31 searches the list table 52 to find, amongthe saved tag IDs, a tag ID for which the read flag F is “0” and thenumber of communication attempts n the highest. In Act 60, the processor31 determines whether the number of communication attempts n of thesearched tag ID exceeds the predetermined number N. The predeterminednumber N is a value approximately equal to the number of readingattempts which can be assumed to be made while an RFID tag 4 is normallyconveyed together with the label paper 1 along the conveyance path 20 topass through the communication available area Aa of the first antenna21.

If the number of communication attempts n of the tag ID does not exceedthe predetermined number N (NO in Act 60), the processor 31 proceeds toAct 61. The processor 31 rewrites all the read flags F described in thelist table 52 to “0” in Act 61. Thereafter, the processor 31 returns toAct 53 and repeats the processes.

If the number of communication attempts n of the tag ID exceeds thepredetermined number N (YES in Act 60), the processor 31 proceeds to Act62 and identifies an unprocessed tag ID as the target tag ID and writesthe target tag ID to the target tag area of the memory 32. Then, in Act63, the processor 31 deletes the record of the identified target tag IDfrom the list table 52. Thereafter, the processor 31 activates thewriting process in Act 64 in the same manner as that in the firstembodiment (see FIGS. 6 and 7).

After the writing process is executed and the label 3 is dispensed, theprocessor 31 determines whether the label dispensing process has beencompleted (Act 65). If the label dispensing process has not yet beencompleted (NO in Act 65), the processor 31 proceeds to Act 61 andrewrites all the read flags F described in the list table 52 to “0” andreturns to the process of Act 53 to repeat the processes.

Once the label dispensing process is complete (YES in Act 65), theprocessor 31 proceeds to Act 66 and stops the motor 15 to stop theconveyance of the label paper 1.

In the RFID tag communication device 200 according to the secondembodiment, the first antenna 21 and the second antenna 22 are providedin that order from the upstream side of the conveyance direction Y alongthe conveyance path 20. Then, the shielding plate (or the shieldingportion) 62 is provided so that the radio wave emitted from the firstantenna 21 is blocked in the communication unavailable area Ab formed onthe conveyance path 20 while the part of the communication availablearea Aa (or the limited communication available area Aa) is left on theconveyance path 20 by, for example, the opening 63 of the shieldingplate 62 (see FIG. 8). Then, the controller 30 identifies the tag IDread from the RFID tag 4 that passes through the limited communicationavailable area Aa by the communication via the first antenna 21. Forexample, the controller 30 identifies the tag IDs for which the numberof reading attempts n via the first antenna 21 exceeds the predeterminednumber N. If such a tag ID has been identified, the controller 30designates the tag ID by communication via the second antenna 22. Thecontroller 30 writes the tag writing data to this RFID tag 4 by thedesignation of the tag ID.

Also, the RFID tag communication device 200 of the second embodiment canachieve the same or substantially the same effects as those in the RFIDtag communication device 100 of the first embodiment. Additionally, inthe second embodiment, since the limited communication available area Aacan be made narrower by the shielding plate 62 such that only one singletag ID is read by the first antenna 21, compared with the firstembodiment in which a plurality of tag IDs might be read by the firstantenna 21, there is an advantage of reducing the process load of theprocessor 31 of the RFID tag communication device 200. In the firstembodiment, there can be an advantage in that the structure of theshielding plate 61 may be simpler and smaller than the shielding plate62 of the RFID tag communication device 200.

Third Embodiment

FIG. 13 depicts a part of a RFID tag communication device according to athird embodiment. Portions common to the first embodiment are designatedwith the same reference numerals, and the descriptions thereof are notrepeated. A difference in configuration of the third embodiment from thefirst embodiment is that a second shielding plate 64 is provided facingthe shielding plate 61 with the conveyance path 20 sandwichedtherebetween. In this manner, by sandwiching the conveyance path 20between the shielding plate 61 and the second shielding plate 64, aradio wave that may circumvent the shielding plate 61 and reach the RFIDtag 4 on the conveyance path 20 can be effectively shielded. Therefore,the radio wave from the first antenna 21 to the RFID tag 4 can beshielded more securely than in the case of the first embodiment.Accordingly, the reliability of the RFID tag communication device 100can be further improved.

Fourth Embodiment

FIG. 14 depicts a part of a RFID tag communication device according to afourth embodiment. Portions common to the first embodiment aredesignated with the same reference numerals, and the descriptionsthereof are omitted. A difference in configuration of the fourthembodiment from the first embodiment is that the first reader and writer23 and the second reader and writer 24 are combined to a third readerand writer 25. A switch 71 is also provided to a line that connects thethird reader and writer 25 with the first antenna 21 and the secondantenna 22. The switch 71 is controlled by the controller 30. Forexample, the controller 30 controls the switch 71 to connect the firstantenna 21 to the third reader and writer 25 during the processes fromAct 1 to Act 31 in FIGS. 5 and 6. Then, when the controller 30 startsthe process of Act 32, the controller 30 controls the switch 71 toconnect the second antenna 22 to the third reader and writer 25. Whenthe writing of the tag writing data ends, the controller 30 controls theswitch 71 to connect the first antenna 21 back to the third reader andwriter 25.

A switch control unit that controls the switch 71 may be included in ormay not be included in the controller 30. In the latter case, the thirdreader and writer 25 may include the switch control unit so as tocontrol the switch 71 based on a command received from the controller30.

The fourth embodiment can achieve the same or substantially the sameeffects as those of the other present embodiments. In addition,according to the fourth embodiment, the reader and writers can becombined into one, and thus there is an advantage of reducing the cost.There is also an advantage of reducing the installation space of thereader and writers.

The embodiments are not limited to the first to fourth embodiments.

The first to fourth embodiments generally relate to whether the tag IDof the RFID tag 4 can be read or not by the wireless communication viathe first and second antennas 21 and 22. Regarding this point, in amodified embodiment, even if the controller 30 were able to read the tagID by the wireless communication, the controller 30 might regard thatthe tag ID had not been read and execute processes accordingly, in acase where the radio wave reception intensity is equal to or lower thana predetermined threshold.

In the present embodiments, the communication available area Ad of thesecond antenna 22 does not overlap with the communication availableareas Aa and Ac of the first antenna 21. In a modified embodiment, thesecond antenna 22 may be arranged closer to the first antenna 21 so thatthe communication available area Ad of the second antenna 22 overlapswith the communication available area Aa or Ac of the first antenna 21.In such a case, the distance of the conveyance path 20 from theconveyance roller 12 to the platen roller 14 can be reduced, and theRFID tag communication devices 100 and 200 can be further miniaturized.

According to the first embodiment, the unit of the predetermined numberN to be compared with the number of communication failures n may bechanged to time (e.g., rather than counting individual reading attemptsa length of time during which or for which communication has beenattempted may be tracked). In the same manner, according to the secondembodiment, the unit of the predetermined number N to be compared withthe number of communication attempts n may be changed to time. That is,in the first embodiment, the tag ID for which the elapsed time of thecommunication unavailable state exceeds a predetermined time N may beidentified. In the same manner, in the second embodiment, a tag ID forwhich the elapsed time of the communication available state exceeds apredetermined time N may be identified.

While in the present embodiments, the RFID tag 4 to be conveyed alongthe conveyance path 20 is provided on the label 3, in some cases, theRFID tag 4 may not be necessarily provided on the label 3. For example,the RFID tag 4 can be provided on a sheet-shaped paper or the like whichis sequentially conveyed. In such a case, the first antenna 21 and thesecond antenna 22 are arranged along the conveyance path 20 so that thesame or substantially the same effects are achieved as those in thepresent embodiments. Alternatively, the RFID tag can be independentlyconveyed on the conveyance path 20 where the first antenna 21 and thesecond antenna 22 are arranged to obtain the same or substantially thesame effects as those in the present embodiments.

The process to be executed by the controller 30 via the second antenna22 is not limited to the writing process of the tag writing data. Forexample, a process of reading data pre-stored in the RFID tag 4 otherthan the tag ID or a process of updating the data that has been readfrom the RFID tag 4 and rewriting it to the RFID tag 4 is applicable.

The material of the shielding plates 61 and 62 is not limited to metal.Any material that can shield radio waves emitted from the first antenna21 in order to form the area where the communication between the firstantenna 21 and the RFID tag 4 on the conveyance path 20 is notestablished, such as the communication unavailable area Ab, can be used.

While certain embodiments have been described, these embodiments havebeen presented by way of example only and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A wireless tag communication device, comprising:a first antenna configured to emit radio waves towards a first region ofa conveyance path for wireless tags; a second antenna configured to emitradio waves towards a second region of the conveyance path on adownstream side of the first region in a tag conveyance direction alongthe conveyance path; a shield configured to block the radio wavesemitted from the first antenna from reaching a first portion of thefirst region while permitting the radio waves from the first antenna toreach a second portion of the first region; and a controller configuredto: select a tag ID read from a wireless tag on the conveyance path viathe first antenna as a target tag ID, designate the target tag ID bycommunication via the second antenna, and write tag information via thesecond antenna to the wireless tag corresponding to the designatedtarget tag ID.
 2. The wireless tag communication device according toclaim 1, wherein the controller is further configured to: control thefirst antenna to emit an interrogation wave; receive a plurality ofresponse waves from a plurality of wireless tags via the first antenna;and select the target tag ID from among the plurality of wireless tagsproviding a response wave to the interrogation wave.
 3. The wireless tagcommunication device according to claim 1, wherein the controller isfurther configured to: control the second antenna to emit aninterrogation wave designating the target tag ID; and receive a responsewave from the designated target tag via the second antenna in responseto the interrogation wave designating the target tag ID.
 4. The wirelesstag communication device according to claim 3, wherein the controller isfurther configured to write data to the target tag ID once the responsewave from the designated target tag is received.
 5. The wireless tagcommunication device according to claim 1, wherein the wireless tags areRFID tags.
 6. The wireless tag communication device according to claim1, wherein the controller selects the tag ID of a wireless tag on theconveyance path as the target tag ID based on the wireless tag passingthrough the first portion of the first region.
 7. The wireless tagcommunication device according to claim 1, wherein the first portion ofthe first region is at the center of the first region.
 8. The wirelesstag communication device according to claim 1, wherein the first portionof the first region surrounds the second portion of the first region. 9.The wireless tag communication device according to claim 1, wherein thecontroller is configured to track the number of communication attemptsfor each tag ID read via the first antenna and select the tag ID of awireless tag with the most attempts as the target tag ID.
 10. Thewireless tag communication device according to claim 1, wherein thecontroller is configured to track the number of communications for eachtag ID read via the first antenna and select the tag ID of a wirelesstag with a number of communications above a threshold value as thetarget tag ID.
 11. The wireless tag communication device according toclaim 1, wherein the shield has an opening in a central portion thereof.12. The wireless tag communication device according to claim 1, furthercomprising: a first tag reader/writer connected to the first antenna;and a second tag reader/writer be connected to the second antenna. 13.The wireless tag communication device according to claim 1, furthercomprising: a switch connected to the first and second antennas; and atag reader/writer connected to the switch, wherein the controller isfurther configured to control the switch to selectively connect the tagreader/writer to first or second antenna.
 14. The wireless tagcommunication device according to claim 1, further comprising: a secondshield opposite the shield, the conveyance path passing between thefirst and second shields with the first region being between the firstand second shields.
 15. An RFID tag communication device, comprising: afirst antenna configured to radiate first radio waves toward aconveyance path for a plurality of RFID tags such that a firstcommunication area is formed along the conveyance path; a second antennaconfigured to radiate second radio waves toward the conveyance path suchthat a second communication area is formed along the conveyance path; ashield blocking part of the first radio waves such that first radiowaves does not reach a portion of the conveyance path otherwise withinthe first communication area; and a controller configured to: select atarget RFID tag that becomes unreadable via the first antenna duringconveyance of wireless tags along the conveyance path within the firstcommunication area; and write data to the selected target RFID tag viathe second antenna.
 16. The RFID tag communication device according toclaim 15, wherein the controller selects the target RFID tag based onthe number of failed communication attempts via the first antenna forthe target RFID tag being above a predetermined threshold.
 17. The RFIDtag communication device according to claim 15, wherein the controllerselects the target RFID tag based on the number of communications viathe first antenna with the target RFID tag.
 18. A wireless tagcommunication device, comprising: a first antenna configured to radiatefirst radio waves toward a conveyance path for a plurality of wirelesstags such that a first communication available area is formed along theconveyance path where communication via the first antenna can beestablished with the wireless tags as the wireless tags pass along theconveyance path through the area; a second antenna configured to radiatesecond radio waves toward the conveyance path such that a secondcommunication available area is formed along the conveyance path wherecommunication via the second antenna can be established with thewireless tags as the wireless tags pass along the conveyance through thearea; a shield to block the first radio waves from reaching a portion ofthe conveyance path so as to form a communication unavailable areawithin the first communication available area; and a controllerconfigured to: identify tag IDs of the wireless tags that are readablevia the first antenna; select a target tag ID from among the identifiedtag IDs; and write information to the wireless tag corresponding to theselected target tag ID via the second antenna.
 19. The wireless tagcommunication device according to claim 18, wherein the controllerselects the tag ID of the wireless tag for which the number ofcommunication attempts via the first antenna exceeds a predeterminedthreshold.
 20. The wireless tag communication device according to claim18, wherein the wireless tag is an RFID tag.